The present invention relates to a machine for injection molding an end closure in which a recloseable tab of the end closure is molded in an open position and is subsequently rotated to its closed position before the end closure is ejected from the mold cavity.
Thermoplastic injection molding machines are commonly used for molding a one piece end closure in which the tab for closing the end closure is molded in an open position. One such machine is shown in U.S. Pat. No. 3,537,676. A disadvantage of these prior art machines is that it is necessary to close the recloseable tab of the end closure after the end closure is ejected from the mold. This necessitates an additional operation on the end closure after it is ejected from the mold.
The present invention departs from these and other prior art machines and methods by providing an injection molding machine having a stationary mold half and a movable mold half. The stationary and movable mold halves cooperatively define a mold cavity for an end closure article having a base and a recloseable tab disposed in an open position relative to the base. After the end closure article is molded, the mold is opened and the recloseable tab is moved to its fully closed position. The end closure article is then ejected from the open mold cavity and is ready for assembly on a container without requiring any further operations.
Further in accordance with the principles of the invention, the stationary mold half includes a tab lifter which engages a portion of the tab to rotate the tab from its open position as the movable mold half moves from a molding position adjacent the stationary mold half to an ejecting position spaced away from the stationary mold half. After the tab lifter moves the tab to a partially closed position, a tab closing roller engages the tab and further rotates the tab to its fully closed position. The end closure with the tab in its fully closed position is then ejected from the open mold cavity.